Calipering mechanism



June 11, 1935. ARMS Er AL 2,004,361

CALIPERING MECHANISM Filed June 17, 1952 7 Sheets-Sheet 2 ZZZ/67% $55072 2 157020072 1 72 JZJZWIZJ June 11, 1935. M, H ARMS Er AL 2,004,361

CALIPERING MECHANISM Filed June 17, 1932 7 sheets sneet 5 Y I! I,

' "I E V IIIIII June 11, 1935. H A r AL CALIPERING MECHANISM Filed June 17, 1932 7 Sheets-Sheet 4 June 11, 1935. v HARMS r AL 2,004,361

CALIPERING MECHANISM Filed June 17, 1932 7 Sheets-Sheet 5 3 IIII /f/gzLij June 11, 1935 ARMS AL CALIPERING MECHANISM 7 Sheets-Sheet 6 $2067 3? J5J 07z EJ527200 J7 iv Filed June 17,' 1952 297%72 JZ 7 m waif June 1 l, 1935. M. H. ARMS El AL I .CALIPERI-NG MECHANISM Filed June 17, 1932 7 Sheets-Sheet I to both.

Patented June camnamo I j Merton H. Armgand field, Vt., assignors v Grinder Company,

tion of Vermont MEQHANISM to Bryant chucking Mam. VF"! Application June 17, 1932, Serial No. 817,820

27 Claims.

This invention relates to mechanism for calipering work and more particularly while it is in the machine bywhich it isbeing cut to a desired finished size. It has for an object to effect the measurement by electrical mechanism of great accuracy, but which does not require making or breaking of the measuring circuit for its operation.

Another object is to provide a mechanism of this type applicable to internal grinding.

A still further object is to provide such a mecha .nism applicable to show when the work has reached the proper size for'both rough and finish grinding and which may effect certain machine controls when such sizes are reached and automatically for both rough and finished sizes.

I A further object is to provide a calipering mechanism which may gage from the front of the hole in internal work and which may be moved away from the work when the tool is in operation or the work is to be removed or replaced.

Further objects and advantages will appear from a more complete description of certain embodiments of this invention shown in the accompanying drawings in which Figure 1 isa fragmentary view partly in side evation and partly in section of an internal grinder showing the mounting of a sizing caliper.

Figure 2 is a fragmentary longitudinal-section of a work holder and the contact end portion of one form of caliper.

Figure 3 is a view similar to Figure 2but showing a modification.

Figure 4 is an end elevation of the work holder showing the work and caliper.

Figures 5, 6 and 7 are sections similar to Figure 2, but showing different forms of caliper.

Figures 8, 9 and 10 are end elevations corresponding to Figures 5, 6 and 7, respectively.

Figure 11 is a diagrammatic view showing automatic feed retraction'of the grinding wheel relative to the work when the desired rough and finished sizes have been reached.

Figure 12 is a diagrammatic view of the feed connection from the feed shaft to the wheel carrier.

Figure 13 is a view similar to Figure 6, but showg a diflerent electrical responsive element.

Figure 14 is a view showing a construction somewhatmodified from Figure 13 and showing a diagram of the elec Figure 15 is a view partly in elevation and partly in section showing a front caliper applied to internal work.

Figure 16 is an end elevation of the same.

Figure 17 is a fragmentary view partly broken away of a part of the machine oi? Figures 15 and trical connections applicable Figure 18 is a fragmentary section on line I8-I8 of Figure 17. v

Figure 19 is a detail section on line I B-IO of Figure 15.

Figure 20 is an ing mechanism.

Figure 21 is a view similar to a portion of Figure 15 but showing a different electrical responsive element.

Figure 22 is afragmentary wiring diagram showing a different form of responsive mechanism which may be used in place of portions of Figure 11.

Referring first to Figure 2, at I is shown a work support which may be a portion of a rotary work spindle as therein illustrated. This support is shown as provided with a counterbored portion 2 at its outer end within which may be placed the work W, which is of ring form. The work may be secured in this counterbored portion for rotation with the support and spindle as by means of the screw 3, the head of which bears against the outer face of the work. At 5 is shown the grinding wheel spindle having a grinding wheel 6 at its end which is intended'to work upon the interior of the work ring Wand to grind this to a predetermined diameter. Within the support I is positioned a carrier in which is' shown as axially movable within the support. This carrier is. provided with an enlarged internal chamber II at its outer and across which is placed a diaphragm I2, this being secured in position about its margin by a ring member I3 threaded into the outer end of the chamber II. This diaphragm I2 supports a stem I 4 which extends substantially centrally therethrough and which carries on its outer end a work feeler I5, which preferably is provided with a suitable diaelevation of the caliper-retract- 5 mond point I6 which may be brought into engagement with the internal face of the work. The diaphragm I2 forms a yielding mounting member for the stem and feeler which yieldingly presses the point I 6 outwardly into engagement with the internal face of the work so that as the work is ground away the inner end of the'stem I I moves laterally of the carrier I0 and in between a pair of cores I1 and III of a pair of electromagnet coils I9 and 20. The stem portion between these cores I1 and I8 is of a magnetic material, such as iron,s0 that the distance between the stem and the cores act to vary the relative reluctances of the coils to the passage of an alternating current therethrough, swinging of the stem as the work reaches size acting to progressively decreases the reluctance of the coil 20 and increase the reluctance of the coil I9, As will later be pointed out, this provides a delicate electric indication of the size of the hole in the work, which through any suitable responsive device may be employed to indicate work size and ifdesired alsoto eflect withdrawal of the grinding wheel from the work when the desired size has been' reached. a

' In Figure 3 a modified construction has been shown in which in place of the single magnet coils l9 and 20, two pairs of such coils are employed, the carrier l0 being of sufilcient length to include besides the coils l8 and 20, coils 2i and 22. The stem Na in this construction is also prolonged to pass between the cores of both pairs of coils. As will later more fully appear, one of these pairs of coils may be used to indicate when the roughing size of the work has been reached and the other pair may be used to indicate when the finished size has been reached.

Cooperating with the feeler finger l5 may be a relatively stationary fihger 25, which, in the form shown in Figures 2 and 3, is integral with the diaphragm-retaining ring l3. This single finger acts to prevent the entry of the gage into the work until the hole approaches so near the desired finished size that the indicator may not be injured in passing thereinto. The measuring is thus taken between the carrier and one side of the hole being ground.

In Figure 5 a somewhat modified construction is shown in which the carrier I0 is pivotally connected as on the pin 38 to a sleeve 3| which passes through the work spindle 32, whereas in the construction shown in Figures 2 and 3 the carrier is secured directly to the corresponding sleeve. In the construction shown in Figure 5 also the carrier is somewhat loosely guided within the work support I, and instead of a single finger such as shown at 25 in Figures 2, 3 and 4, a pair of oppositely positioned fingers 53 are employed to prevent the entry of the gage until the hole is nearly the correct size and the measurement is thus across the diameter of the work between the finger l5 and a relatively stationary finger 52 carried by the ring l3 which may be fixed tear integral with the ring l3 and which may be provided with a work-engaging diamond 26.

In Figure 6 a further modification is shown in which instead of mounting the feeler stem on a diaphragm the feeler 48 shown as of angle shape is secured to the carrier 4| by means of a leaf spring 42. One end of this leaf spring is secured as by screws to one arm of the stem 40 and the other is divided, one portion 43 being fixed to the side face of the carrier in a groove 44 therein and the other being bent inwardly and secured to an end face 45 of this carrier. The inturned arm 46 of the stem passes between the cores 41 and 48 of the electromagnet coils 49 and 50, respectively, these being connected to the responsive mechanism similarly to the electromagnet coils l9 and 28 shown in Figures 2, 3 and 5. In this figure also there is shown provided three relatively stationary workengaging fingers 52, 53 and 54, the position of these fingers being shown best in Figure 9 and being integral with a portion of the carrier 4|,

which is recessed to receive threaded therein the electromagnet coil 50. A similar three-finger construction is shown in Figures 5, 6, 8 and 9 and is employed wherever the carrier is pivotally mounted on its stem, the middle finger cooperating with the feeler to measure the diameter of the work and the other fingers preventing entry of the feeler until the work is nearing size as explained with reference to Figure 5.

In Figure 7 a still further modification is shown in which the carrier 60 is rigidly secured to its supporting sleeve similarly to the construction of Figures 2 and 3. and in this form but a single relatively fixed work-engaging finger as at 52 is employed.

'In' Figure 11 is shown somewhat diagrammatically one form of responsive mechanism which may be employed, this being controlled by the position oi. the feeler stem to indicate when the correct work size has been reached, or if desired, also, to withdraw the wheel from the work. As illustrated in this, figure, two controls, one for roughing size and the other for finishing size, have been shown, this corresponding to the showing of Figure 3 in which there are two sets of controlling electromagnets. It should be understood, however,'that when but a single pair of electromagnets are to be employed the mechanism may be simplified accordingly. One or the other of these sets of electromagnets are connected through a switch mechanism in series with solenoids 6| and 62, which are movable relative to magnetic cores 63 and 84, respectively, the circuit receiving alternating current as through a transformer at 85. In the position shown in this figure the electromagnet coils 2| and 22 are in this circuit with the solenoids 8| and 82. When the stem |4a is midway between the cores ,oi. the electromagnets 2| and 22 the reluctances of these electromagnets are equal, the current then being evenly balanced between the electromagnets and equally balanced between the solenoids 6| and 62. If, however, the stem Ma is nearer to one of the coils 2| and 22 than to the other, this reluctance varies and there is a proportionate variation in fiow through the corresponding solenoids GI and 82, thus unbalancing their pulling effect on their cores 83 and 64, causing these solenoids to move and swinging the pointer 88 secured to a lever 69 connecting these solenoids in a corresponding direction and to an amount dependent on the amount of the unbalance of current through the two solenoids. When this unbalance has reached a determined point, a contact arm 10 on the pointer 88 makes contact with a contact II, which may be a mercury cup, which closes a. circuit through the relay I2, which in turn, closes a circuit through a solenoid l8. Energization of this solenoid forces its core 14 to the left, as shown in this figure, swinging an arm 15 into the dotted line position shown in this figure, so that a dog 16 carried thereby falls oil from a stationery retaining plate TI and engages the teeth of a feed wheel I8 on the feed shaft 19 and moves this feed wheel backwardly, thus retracting the grinding wheel from the work. A connection by which this may be accomplished is illustrated somewhat diagrammatically in Figure 12 in which the grinding wheel spindle 5 is shown as supported on an arm 80 turnable about the axis of a supporting bar 8|. The bar 8| may be moved axially to impart the working traverses to the grinding wheel. The arm 80 has an extension 82 provided with a cam follower 88 against which bears a member 84 carried by a feed screw 85. The gear 18 forms part of a nut 18 engaging this feed screw and by the rotation of this nut the arm 80 through its intermediate connections 82 and 85 is caused to impart feed and retracting motions to the wheel shaft 5, depending on the direction of rotation of the gear 18. Rotation of this gear 18 effected by energization of the solenoid is in a direction to retract the grinding wheel. The normal feed motions of the wheel are shown in Figure 11 as produced by a cam acting on an arm 8| pivoted at 82 and carrying at its free Suitable controlling elements '04, and 05may beemployed to limit the motion of the dog "to cause it to produce the desired feed motion.

As soon as the solenoid I3 has been energized and the gear I8 turned to retract the grinding wheel, an abutment I00 carried by the plunger I4 closes the switch IM and energizes the solenoid I02. This acts through the rack bar I03 to throw the switch 60 through an arc of 180, breaking connection to the magnet coils 2| and 22 and making connection to the magnet coils I9 and 20, and near the termination of stroke of the core I05 of the solenoid I02, this core breaks the circuit to both of these electromagnet coils I9 and 20 at the switch I06. This interrupts the holding circuit to the relay 12, die-energizing the solenoid I3 and permitting the spring I01 to return the arm I5 to its inoperative position, and this in turn permits the switch IOI to open, de-energizing the solenoid I02, which permits the rack bar I00 to be returned by the spring I00. A suitable ratchet mechanism is shown at I09 permitting this to be done without moving the switch 00. This permits the switch I 00 to close,

thus re-establishing conditions for control of the mechanism through the size of the work but through the second set of electromagnets I9 and 20. This mechanism each time the desired size is reached causes the wheel to retract from the work and the opposite set of electromagnets is placed into controlling relation with the mechanism. Thus by proper setting of the parts the wheel may be withdrawn from the work first after the work has been reduced to a rough size and then on the next grinding operation the wheel will be retracted when the work has been reduced to the desired finished size. This finished work may then be removed from the machine and a new unground piece placed therein for the next cycle of roughing and then finishing cuts by the grinding wheel.

In Figure 22 is shown a mechanism responsive to variations of impedance in a pair of coilssuch as I9, 20 or 2I, 22 of Figure 11 due to movement I of a feeler actuated stem, somewhat diii'erent from that shown in Figure 11. The line a common to the two opposed electromagnet coils leads through the secondary of an energizing transformer 300 to the mid point of a coil 30I to opposite ends of which are connected the lines b and c from the magnet coils. So long as the imped-.

ances of these magnet coils are equal there is no difference of potential between the ends of the coil 30I. As the stem Ida is moved by contact with the work nearer to one of these coils and further from the other, the impedances of.the

two magnet coils become out of balance, and a potential difference is set up between the ends of the coil 30I. Lines 302 and 303 lead from' these ends to a rectifier of any suitable type at 304, the rectified current due to such potential differences between the ends of the coil 30I passing to the microammeter 305 which indicates the amount of this current and at the proper time closes the contacts at 306 and 301 and closes a circuit to the relay I2 of Figure 11, thus retract- -ing the feed as heretofore described.

Where ,the caliper mechanism is engaged with the work entering from the back end opposite to that end at which the grinding wheel enters, it is desirable to provide means for withdrawing wheel-supporting arm 80 is the sizing min advance of the wheel so that the wheel may grind the full length of the hole in the work and may not strike the sizing mechanism. To

Figure 1 may be employed. Referring to this figure, the bar 0| which carries the slidably and rockably mounted in the frame IIO of the machine and a suitable adjustable abutment III is arranged to be contacted by a suitable portion of this bar, such as the end, when the grinding wheel approaches the inner end of it's traversing path. As shown this abutment comprises a screw threaded into an arm I I2. This arm is slidably mounted on a suitable guide member I I3 and'is normally pressed toward the wheel-carrying arm 00 as by means of a coil spring II hearing ,at one end thereon and at its opposite end against a collar 5 secured to the outer end of' the guide III. This arm I I2 is provided at its opposite end from the abutment I II with a forked portion having enlarged ends at I I6 which engage within a peripheral groove III of a collar IIB fixed to the work spindle I20 which slidably carries the sleeve, as 3 I to which is secured the carrier. for the work feeler. The three conductors a, b and c leading from the measuring electromagnet coils pass through this sleeve and at the opposite end from the indicator these conductors are secured to slip rings I 20, I2I and I22, respectively, on the inner face of a disk I23 either of insulating material or otherwise formed to insulate the slip rings from each other, the disk I23 being secured to the outer end of the carrier sleeve. Normally bearing against these rings are contacts I 24, I25 and I26 to which are secured conductors corresponding to a, b and c and which lead to the solenoids 6| and 62; When the grinding wheel approaches the work feeler, therefore, the bar 8| acting through the arm II2 retracts the feeler from the hole in the work and at the same time operatively disconnects the electromagnets carried thereby from the control circuit, thus to render the feeler fingerinoperative to effect the I indication of the pointer 68, or to operate the tool-withdrawing mechanism. For simplification inthe diagram of Figure 11 this mechanism for breaking the control circuit has not been shown thereon. 1

Instead of employing electromagnet coilsand solenoids and the variations in impedance of their windings by variations of position of the feeler stem-with relation thereto, other electrical devices may be employed, preferably of non-contacting type, that is, those which do not require the making or breaking of electric circuits for spaced electro-conducting plates forming portions of an electrical condenser. In Figure 13, for example, the feeler is shown at I pivotally secured by the spring I5I to the carrier I52, which is slidably guided in the work support I. The in- .wardly turned end I53 of the feeler acts through an adjustable abutment screw I54 on the axially slidable stem I55 mounted in the carrier I52. At its rear end this stem carries the movable condenser plate I56 which cooperates with a stationary annular condenser plate I51. Conductors I60 and I6I lead from these spaced plates through the carrier supporting sleeve.

In Figure 14 the construction is very similar tively stationary work-engaging elements, two of which are shown at I61 and I68, in this respect 7 being similar to the construction shown in Figures 5, 6, 8 and 9, respectively. As shown in Figure 14, the conductors I and IBI are connected in series with an inductance I10 and a radio frequency ammeter indicated diagrammatically at III. This circuit, through the inductance I10, is excited by an oscillator indicated generally at I12, which, as shown, is provided with a coil I13 in inductive relation to the coil I10 of the measuring circuit. The natural frequency of the oscillator I12 is so related to the frequency of the measuring circuit as determined by the relative values of capacity between the measuring plates I56 and I5! and the inductances of this circuit so that as the plates approach each other or separate, as through the action of the spring I15 acting on the stem I55, the natural frequency of the measuring circuit approaches or departs from that of the oscillator. This causes the current induced in the measuring circuit by the oscillator circuit to increase or decrease, depending on the adjustment of the apparatus, resulting in the swinging of the ammeter arm I00 in a direction to make a connection between the contact WI and the mercury cup I82 when the desired work size is reached, this closing a circuit through the relay I82 which actuates any suitable mechanism such as the wheel feed retractive mechanism shown in Figure 11, or other suitable means which may indicate to the operator that the correct size has been reached.

In some cases it may be desirable to cause the indicator mechanism to approach the work from the front, that is, from the side at which the grinding wheel enters the work. Where this is desired mechanism, such as is shown in Figures 15 to 22, may be employed. Referring to these figures, the work feeler as shown comprises an L- shaped element 200 which is secured through a suitable holder 20I to one end of the stem 202. This stem is slidably mounted in the tubular carrier 203 and as shown may be supported by a pair of suitably spaced diaphragms 204 adjacent to opposite ends of the carrier similarly to the diaphragm shown at I2 in Figures 2 and 3. This carrier 203 is shown as mounted in a split sleeve 2I0 which is secured to one end of a rock shaft 2I I. This rock shaft is journaled in a casing 2 I2 having flanges 2I3 by which it may be secured as by the screws 2I4 to a web 2I5 which forms a portion of the grinding machine frame. The rock shaft 2II is designed to be rocked through an angle of approximately 45. At one limit of its position the feeler is presented into engaging relation with the work as shown in full lines in Figure 15. By rocking this shaft 2II', however, it may be turned to the dotted line position shown in Figure 15, or further, if desired, in order to remove it from the front of the work and out of the way.

In order to accomplish such angular motion of the shaft 2 it is shown as having secured thereto a gear 220 within the casing 2 I2 and with which meshes a pinion 22I on a stub shaft 222 also carried by the casing 2I2. Fixed to rotate with the pinion 22I is a gear 223 with which meshes a pinion 224 on the armature shaft 225 of a reversible electric motor 220 by the action of which the rock shaft 2II supporting the carrier 203 may be rocked to and from operative position. Its limit of motion toward its operative position may be determined by an adjustable abutment screw 230 carried by a boss 23I projecting from the casing 2 I2 with which may contact a boss or pad 232 on the member 2I0.

Besides the swinging motion of the sizing indicator from and to operative position it may be desired to hold the feeler point away from contact with the work when it is in operative angular relation thereto. Where thisis desired the construction shown in Figures 15, 16, 1'7 and 18 may be employed. Normally in engagement with the end of an extension piece 2020 of the stem 202 is a rod 24I mounted for axial movement and carrying a stem or finger portion 242 of iron or other magnetic material which is arranged between the electromagnets 243 and 244. These electromagnets may be arranged in a suitable responsive circuit similarly to the electromagnets I0 and 20 or 2I and 22 shown in the mechanism previously described, so that the position of the feeler under normal conditions determines the indications of a suitable indicator or controls for retracting the wheel from the work when the desired size has been reached. A spring 245 may be employed to press the rod 24I into contact with the stem extension 2020, the limit of this motion being determined by engagement of the member 242 against the core of the electromagnet 243. Extending transversely of the carrier 203 is a cam rock shaft 250, which as shown best in Figure 1'7, is cut away to form a cam shoulder 252 which may engage the shoulder portion 240 of the piece 2020, so that by rocking this shaft 250 the stem 202 may be pushed axially away from the rod 24I and against the action of the spring 254 surrounding the stem 202 adjacent to its opposite end. This rocking of the cam shaft 250 to effect such separation and to retract the feeler 200 from the work may be actuated by a crank arm 260 secured to one end of the cam shaft 250 and having its outer end connected through a link 26I (see Figure 16) with a solenoid core or plunger 264 which passes within the solenoid at 265. By energizing this solenoid the plunger 264 is drawn therein, this acting to rock the cam shaft 250 and move the feeler 200 away from the work although the carrier may be in operative angular relation thereto.

Instead of employing the electromagnets 243 and 244, as shown in Figure 15, relatively movable condenser plates may be employed, as in the mechanism shown diagrammatically in Figure 14. 'Such a construction is shown in Figure 21, where the movable condenser plate 210 is secured to the feeler stem 202 and the fixed plate 2' is secured to the carrier 203. In the form shown in this figure there is no provision for separating the'feeler from the work while its carrier is in operative angular operative relation thereto, but it is evident that an arrangement similar to that shown in Figures 15, 16, 17 and 18 might be employed if desired.

From the foregoing description of certain embodiments of this invention, it should be evident to those skilled in the art that various changesand modifications might be made without departing from the spirit or scope of this invention as defined by the appended claims.

We claim:

1. In combination with a tool, a work holder, and means for relatively feeding and retracting said tool and work holder, of a work-engaging feeler, a relatively movable element responsive in position to the position of said feeler when said i'eeler is in engagement with the work, a pair of in relatively fixed means arranged in spaced relation and coacting with said movable element, and electrical means responsive to the relative positions of said relative movable element and one or the other of said fixed means for retracting said tool relative to the work when the work has been reduced to a desired rough or finished di-' ments relative to the fixed elements of one or the other of said pair for indicating when the work has been reduced to a desired rough or finished dimension, mechanism for making operative connection sired rough or finished dimension, and means for causing said two pairs 01' fixed elementsfto be alternatelyeii'ective with said movable element. I

5. In combination with a tool, a rotary work holder for tubular work, and means for efiecting platesi'or indicating when the work has been reduced to a predetermined dimension.

6. In combination with a tool, a rotary work movementot said wheel through, the work.

12. In combination, a carrier, means for pivotally supporting said carrier, means for swing ing said carrier about its pivot, a work feeler movably carried by said carrier to be moved by swinging of said carrier into and out ofengaging relation to work, a device carried by said carrier normally responsive to the position of said feeler when in work-engaging relation, means actuable to move said feeler relative to said carrier out of operative relation to the work and out of operative relation to said responsive device, and electrical mechanism for actuating said feelermoving means.

13. In combination, a carrier, a stem movable axially of said carrier, a work feeler operatively related to said stem to cause motion of said feeler to move said stem, spring means yieldingly pressing said stem in one direction,'a responsive device having an axially movable rod against which said stem normally engages, a spring yieldingly pressing said rod toward said stem, and means engageable with the adjacent end of said stem actuable to separate said stem and rod and to move said stem against the action of said spring means.

14. In combination, elements comprising a carrier and a work feeler, a diaphragm secured around its periphery to one of said elements and substantially centrally to the other of said elements, and a device responsive to the position of said work feeler with reference to said carrier.

15. In combination, elements comprising a carrier and a work feeler, a pair of spaced diaphragms each secured around its periphery to one of said elements and substantially centrally to the other of said elements, and a device responsive to the position of said work feeler with reference to said carrier.

16. In combination, a carrier, a diaphragm supported about its margin by said carrier, a work feeler carried by the central portion of said diaphragm, and a device responsive to the position of said feeler with reference to said carrier.

17. In combination, a carrier, a pair of spaced diaphragms each supported about its margin by said carrier, a work feeler carried by the central portion of each diaphragm, and a device responsive to the position of said feeler with reference to said carrier.

18. In combination, a carrier movable in the direction of the axis of hollow work, a work feeler device yieldingly carried by said carrier, and means on said carrier for preventing the entrance of said device into said work until said work has been cut to a predetermined internal diameter.

19. In combination, a carrier movable inthe direction of the axis of hollow work, a work feeler yieldingly carried by said carrier, and a part carried by said carrier in position to strike on the end of the work until the work has been cut to a predetermined diameter thus to prevent the entranceof said feeler into said work until such predetermined diameter has been reached.

20. In combination. a tool, a work holder, a rotary spindle carrying said work holder, a feeler carried by said spindle for engagement with work carried by said holder, a device carried by said spindle in proximity to a portion of said feeler, and means responsive to the relative positions of said feeler portion and device for indicating when the work has been out by said tool to a predetermined size.

21. In combination, a tool, a work holder, a rotary spindle carrying said work holder, a feeler carried by said spindle for engagement with work carried by said holder, a device carried by said spindle in proximity to a portion of said feeler, and means responsive to the relative positions of said feeler portion and device for. separating the tool and the work when the work has been cut by said tool to a predetermined size.

2 2. In combination, a tool, a work holder, a rotary spindle carrying said work holder, and an electrical condenser of variable capacity rotatable with said spindle, a feeler carried by said spindle for engagement with work carried by said holder and controlling by its position the capacity of said condenser, and means responsive to the capacity of said condenser for indicating when the work has been out to a predetermined size.

23. In combination, a tool, a work holder, a retary spindle carrying said work holder, and an electrical condenser of variable capacity rotatable with said spindle, a feeler carried by said spindle for engagement with work carried by said holder and controlling by its position the capacity of said condenser, and means'responsive to the capacity of said condenser for separating the tool and work when the work has been cut to a predetermined size.

24. In combination, a tool, a rotary spindle, a holder for supporting tubular work carried by said spindle, a gage mechanism Within and movable axially of said spindle, said gage mechanism comprising a feeler for engagement with the inner face of the work and an electrical device responsive to the position of said feeler relative to the axis of said spindle, and means controlled by said device for indicating when the hole in the work has been cut to a predetermined size.

25. In combination, a tool, a rotary spindle, a holder for supporting tubular work carried by said spindle, a gage mechanism within and movable axially of said spindle, said gage mechanism comprising a feeler for engagement with the inner face of the work and an electrical device responsive to the position of said feeler relative to the axis of said spindle, means for effecting traverse between said tool and work on said holder, means controlled by said device for indicating when the hole in the work has been cut to a predetermined size, and means for moving said mechanism axially of said spindle intime with such traverse to prevent contact between said feeler and said tool.

26. In combination, a tool, a rotary spindle, a work holder carried by said spindle, a work gage mechanism movable axially of said spindle, said mechanism comprising a feeler for engagement with the work and an electrical device responsive to the position of said feeler relative to the axis of said spindle, means for efiecting traverse of said tool and work, means for moving said mechanism and spindle relatively axially of said spin- 

